Automatic hammer safety for automatic guns



April 1, 1952 A. F. GAIDOS 2,590,854

- AUTOMATIC HAMMER SAFETY FOR AUTOMATIC GUNS Filed July 3, 1946 4Sheets-Sheet l "Fig Alun zmFl E nidns April 1952 A. F. GAIDOS 2,590,854

AUTQMATIC HAMMER SAFETY FOR AUTOMATIC GUNS Filed July 5, 1946 4Sheets-Sheet 2 .A III I.

I AlclnzhE Euillzs WMMWM April 1, 1952 A. F. GAIDOS 2,590,354

AUTOMATIC HAMMER SAFETY FOR AUTOMATIC GUNS Filed July 3, 1946 4Sheets-Sheet 5 April 1, 1952 A. F. GAIDOS 2,590,854

AUTOMATIC HAMMER SAFETY FOR AUTOMATIC GUNS Filed July 3, 1946 4Sheets-Sheet 4 55?; w 555E v iii; I\

525% E E! N Alonzo ET. Euidus Patented Apr. 1, 1952 AUTOMATIC HAMIVIERSAFETY FOR AUTOMATIC GUNS Alonzo F. Gaidos, Redwood City, Calif.

Application July 3, 1946, Serial No. 631,281

1 Claim.

trol mechanism for firearms of the semi-automatic type. There are manyfirearms of the semi-automatic type which have been converted to providefull automatic fire. However, such conversion usually necessitatesalteration of existing major parts of the firearm as well as providingnew additional parts. Further, known conversions are not entirely safeinasmuch as the hammer is not positively blocked in automatic fireduring the intervals that the breech is unlocked. Thus it is possiblefor such hammer to prematurely fire the weapon before the bolt is fullylocked due to failure to close.

Accordingly, it is an object of this invention to provide a simple firecontrol mechanism to convert a semi-automatic firearm to selectivelyobtain full automatic fire without the necessity of performing majormachining operations on existing components.

Another object of this invention is to provide a fire control mechanismfor a firearm that positively blocks the hammer until the bolt is fullylocked for each round fired, thereby substantially eliminating anydanger of premature discharge of the firearm.

A particular object of this invention is to provide a fire controlmechanism for a firearm commonly known as the U. S. Carbine, Cal. .30,Ml, which as issued, affords only means to fire the Weaponsemi-automatically.

Another object of this invention is to provide a fire control mechanismfor a firearm which is controlled by the position of the operating slideof such firearm.

The specific nature of the invention as well as other objects andadvantages thereof will clearly tracted position and the hammer latch isengaged by the hammer.

Fig. 2 is a fragmentary detail View showing the forward end of theactuating bar engaging the front end of the inertia member of thefirearm.

Fig. 3 is a fragmentary detail top elevational (Granted under the act ofMarch 3, 1883," as

amended April 30, 1928; 370 0. G. 757) most position.

view of the trigger guard shown with thhammer removed to illustrate theselector mechanism;

Fig. 4 is a fragmentary detail cross-sectional view taken along the linei-d of Fig. 1.

Fig. 5 is a fragmentary detail view shown partly in longitudinal sectionto illustrate the conventional sear mechanism of the firearm.

Fig. 6 is a detail fragmentary view of Fig. 1 showing the hammer latchreleased fromengagement with the hammer bythe actuating bar.-

Fig. '7 is a side elevational view of the firearm illustrating amodification of the embodiment shown in Fig. 1.

Fig. 8 is a perspective view of the hammer latch.

Fig. 9 is a cross sectional view taken along the line 9-9 of Fig. 3. g

Fig. 10 is a detail perspective View of the hammer latch stud of Fig.'7.

Fig. 11 is a sectional view taken along the line HH of Fig. 1. x .1,

Fig. 12 is a fragmentary detail View showing the hammer latch holdingthe hammerin the cooked position and the actuating bar in the rear- Fig.13 illustrates a third modification of this invention and is shown insideelevation mounted on the firearm with the hammer in the releasedposition. 1

Fig. 14 is a top elevational View of thetactuating bar shown in Fig. 13.

Fig. 15 is a fragmentary view of Fig. 13 showing the hammer in thecooked position and with the actuating bar in engagement therewith.

Fig. 16 is a side elevational view of the firearm embodying a fourthmodification-of this invention, the hammer being in the releasedposition.

Fig. 17 is a top ele'vational view of the actuating bar illustrated inFig. 16.

Fig. 18 is a view similar to Fig. 16 showing the hammer in the cockedposition and the latch in engagement with such hammer.

Fig. 19 is a perspective view of the selector.

While not limited thereto, the invention is particularly appli d tosemi-automatic firearms of the type having a reciprocating operatingslide which functions the boltbetween its locked, battery position, andan unlocked, recoiled position.

The invention to be described in more detail later essentially comprisesan actuating bar mounted along one side of the firearm adjacent thereceiver, one end of such bar being connected to the operating slidewhile the-other end is connected to a hammer latch. The hammer latch ispivotally mounted on the; trigger guard of such firearm. A cam isprovided at the rear end of the actuating bar wherein an arm of thehammer latch is secured, such cam being provided to actuate the latch. Aselector is provided to shift the position of the sear to selectivelyproduce either semi-automatic or full automatic fire, as will beexplained in more detail later. The hammer latch is utilized inautomatic fire to block the hammer until such time as the bolt has beenpositioned in its locked position by the operating slide before releaseof such latch is effected by the actuating bar to prevent prematureignition of a cartridge.

In Fig. 1 there is shown in assembled relation 2. firearm of thesemi-automatic type embodying this invention. The major elements of suchfirearm are substantially identical to the U. S. Carbine, Cal. .30, M1which, as is commonly known, is constructed to fire semi-automatically.Such firearm comprises mainly a receiver I, a barrel 2, a bolt 3 and a.trigger guard 4. Barrel 2 is threadably secured to receiver I in aconventional manher and trigger guard 4 is mounted on the underside ofreceiver I. oppositely disposed ribs 5 (Fig. 4) provided on the rear endof receiver I engage corresponding ways 6 in trigger guard 4. Theforward end of such trigger guard is secured to the receiver by atransverse headed pin 1 Bolt 3 is horizontally mounted within receiver Iand reciprocates therein on suitable horizontal ways provided on theinterior of such receiver. on the underside of barrel 2 there isslidably mounted an operating slide II and such slide is connected tobolt 3 by the rearwardly projecting offset handle portion I la of suchslide. The elements thus far described are all conventional.

In the preferred modification of this invention, an actuating bar I4 isprovided which is slidably mounted on the left side of receiver I asshown in Figs. 1 and 2. The forward end of bar I4 terminates in a hookI5 which is bent inwardly and engages the forward end of operating slideII. The rear end IB of bar I4 is of substantially greater width. Aforwardly opening slot I1 is provided on the front end of enlargedportion I8 which is engaged by headed pin 1. The wood of the stock (notshown). prevents removal of the pin. A cam slot I8 is out in portion It.The forward end of cam slot I8 is enlarged to permit assembly ofactuating bar I4 to a hammer latch I9.

A conventional trigger 2I and sear 22 as shown in Fig. 5 are pivotallymounted in trigger guard 4 on a novel selector 23. A sear spring 31 ismounted between sear 22 and trigger 2I urging sear 22 forwardly.Selector 23 comprises a shaft portion 24 and a knob portion 25, suchknob portion being preferably formed integrally with shaft 24 andlocated exteriorly of the trigger guard to permit convenient manualrotation thereof. Shaft-24 is of enlarged diameter immediately adjacenta hub I2 provided on the inside face of knob 25 as shown at 26. Acentral portion 21 of shaft 24 is eccentrically formed with respect tothe axis of shaft 24. The eccentric portion 21 passes through aslot-like hole 28 in sear 22. Two oppositely disposed notches 2-9 areprovided on hub I2 each of which is selectively engaged by adetent 3| tobe later described. Rotation of selector 23 between two 180 displacedpositions indicated by notches 29 moves sear 22 longitudinally toselectively permit normal semi-automatic fire of the firearm or fullautomatic fire as will be later described.

Hammer latch I8 is a lever-like member (Fig. 8) 'pivotally mounted at"the rear end thereof on large diameter portion 26 of selector 23. Afixed headed stud 32 projects transversely from the forward end of latchI9. Such stud engages the cam slot I8 when actuating b'ar I4 isassembled to the gun by inserting the headed portion of stud 32 throughthe enlarged hole 26 in cam slot i8 and then sliding bar I4 forwardly toengage pin I in slot I1 and hook end I5 with slide II. An inwardlyprojecting lug or ear 33 is provided approximately in the center oflatch I9 and is shaped to engage the hammer 34 of the firearm andprevent hammer 34 from rotating forwardly to fire the gun except whenthe bolt is in battery position, as will be presently described. Detent3! is formed by bending one end of a torsion spring 35. Such springismounted on a pin 3; which is also utilized to pivotally mount hammer34. The other end of torsion spring 35 is hooked about trigger guard 4as shown in Fig. 3.

For semi-automatic fire, selector 23 is turned as shown in Fig. 6. Insuch position detent 3| engages one of the notches 29 thereby yieldinglysecuring selector 23 in the selected position. Eccentric portion 21 onsuch selector 23 is then in a forward position, and as such eccentriclies within slot-like hole 23 of sear 22, the sear is biased forwardlyby sear spring 31. When hammer 34 is rotated rearwardly about pin 36 byrecoil movement of the bolt 3, the forward end of sear 22 engages a searnotch 38 provided on the lower rear end of hammer 34. Sear 22 is forcedrearwardly by the greater bias of hammer spring 46 and the rear endthereof then comes to rest on top of an upstanding projection 39provided on trigger 2 I.

Vfhen such trigger is pulled rearwardly, the forward end of sear 22 isdisengaged from sear notch 38 releasing hammer 34. As the load of hammerspring 4!] is removed from sear 22, the bias of sear spring 3'! urgessear 22 forwardly so that the rear end of sear 22 drops off projection352. 0n the recoil stroke of bolt 3, the forward end of sear 22 againengages sear notch 38 of hammer 34 thereby holding such hammer in thecooked position irrespective of the fact that the trigger remainspulled. Hammer 34 cannot be released until the pressure of the finger isremoved from trigger 2I because sear 22 is in the so-called disconnectedposition. That is, the rear end of sear 22 lies forward of and abuttingtrigger projection 39 and sear 22 cannot be disengaged from hammer 34until trigger 2! is permitted to move forwardly sufficiently to permitthe bias of hammer 3.4 to force the rear end of sear 22 rearwardly ontoprojection 39. Then sear 22 can be released and the gun fired by anotherpull on trigger 2 I.

To effect automatic fire, selector 23 is rotated in which positiondetent 3| then engages the other notch 22 on the selector. Such rotationmoves eccentric portion 27 of selector shaft 24 rearwardly, hencelimiting the forward movement of sear 22. In this position, when triggerM is pulled rearwardly and held there by pressure of the finger, thefront end of sear 22 will disengage from sear notch 38. However sear '22is prevented from moving forward to a cooking position relative tohammer 34 by eccentric 2'! and hence sear 22 does not re-engage hammer24 until trigger '2I is again released. Thus it is apparent thatchanging the longitudinal position of sear 22 by rotation of selector 23will provide semi-automatic or full automatic fire respectively. It isdesired to point out that full automatic fire can be stopped at will bysimply releasing the trigger which brings the front end of scar 22 intothe path of notch 38 of the hammer and permits hammer 34 to force therear end of sear 22 onto projection 39 thereby holding hammer 34 in thecooked position ready for release by the next pull of the trigger.

In full automatic fire, it is apparent to one skilled in the art thatsear 22 is disengaged en- .tirely from hammer 34, and if no other meanswere provided, the hammer would follow the bolt, firing the gun when theforward movement of the bolt was arrested, independent of whether thebolt is fully rotated into its locked position. Hence it is highlydesirable to momentarily delay the fall of hammer 34 until bolt 3 isfully locked, otherwise there would be danger of premature discharge ofthe cartridge with harmful results, or at any event, a lighter blowwould be imparted by the hammer since it would follow the bolt forward.

Hammer latch I 9 therefore is arranged to hold hammer 34 in the cookedposition until bolt 3 is fully locked before such hammer is released.This action is effective in both automatic and semiautomatic fire. Whenoperating slide I I drives rearwardly upon discharge of a cartridge fromforce imparted by a piston (not shown), hammer 34 is rotated to itscocked position by bolt 3. If trigger ZI is not held rearwardly, sear 22will engage sear notch 33 thereby hold ng hammer 34 in the cockedposition until release of such is effected by pulling trigger 2i. hand,if trigger 2| is held rearwardly when bolt 3 recoils, hammer 34 will notbe held cocked by sear 22.

However, as slide Ii is forced rearwardly, the

rear end of such slide strikes an integral lug 4i provided on the insideof bar I4 just slightly ahead of receiver I as shown in Fig. 11. Henceslide I I forces bar I4 rearwardly. A recess I5 provided on the leftside of hammer 34 allows lug 33 of latch I9 to clear hammer 34 as suchhammer is rotated rearwardly in a clockwise direction. As bolt 3approaches the rear end of its recoil travel, cam slot I8 provided inthe rear end I6 of actuating bar I4 forces latch I9 downwardly in acounterclockwise direction so that lug 33 of such latch engages hammer34 slightly below recess I5. Thus hammer 34 is held in a cooked positionuntil the face No of operating slide, returning to' the batteryposition, strikes hook I5 on the forward end of bar I4. Actuating bar I4is then carried forwardly and cam slot I8 raises hammer latch I9 in aclockwise direction so that lug 33 will be raised out of engagement withhammer 34. Hence the bias of hammer spring 40 drives hammer 34 forwardlyto strike a firing pin (not shown).

The cocking of the hammer is accomplished near the end of the recoilstroke as explained above and while the hammer 34 is rotating in aclockwise direction, the latch i9 is rotating counterclockwise wherebythe lug 33 of latch I9 passes arcuately through recess I5 of hammer 34and stops a short distance in front of the hammer below recess I5.Therefore when the bolt 2 starts forwardly into the battery position,the hammer also starts forwardly but after the hammer travels a shortdistance it is stopped and held by the lug 33 of latch I8 until theactuating bar I4 rotates latch I9 clockwise thereby disengaging suchhammer.

It is desired to point out that in semi-automatic fire, lug 33 of latchI3 is similarly disengaged from hammer 34 but due to the high speed ofthe action, such takes place before trigger 2I can be released andpulled again, hence latch On the other 6 I9 is in effect inoperative insemiautomatic fire as far as the operator is concerned.

In Figs. 7 and 12 there is shown in assembled relation a modification ofthe arrangement above 5 described. In this modification substantiallythe same components are utilized as those described with the exceptionof the actuating bar. Selector 23 is again utilized to change sear 22from automatic to semi-automatic fire positions. A hammer latch 43 (Fig.similar to hammer latch I9 is provided which, however, has asubstantially different stud 44 secured to the forward end of suchlatch, such stud 44 being of greater length and diameter. An annulargroove 45 is provided near the outer end of such stud and one end of atorsion spring 48 is mounted on hammer pin 33. Spring 46 extendsrearwardly in a horizontal plane and terminates in a detent 41. Suchdetent engages selector 23 in a manner similar to detent 3I and servesto yieldingly retain selector 23 in one of two positions.

An actuating bar 48 is mounted underneath receiver I on the left of suchreceiver. Bar '48 is a narrow strip-like member and the forward end 49thereof is of slightly reduced width and is preferably rounded. End 49of bar 48 is pivotally secured to the rear of operating slide I I by atransverse pin 54.

Trigger guard 4 is normally cut away as shown at SI and the cutawayportion permits actuating bar 48 to lay snugly against the triggerguard. A substantial portion of the rear end of actuating bar 48 is ofreduced width as shown at 52. A sloped cam surface 53 is provided on theextreme rear end of bar 48. The forward end of reduced width portion 52is sloped upwardly as shown at 54. When the assembled action is placedwithin the stock of the firearm (not shown) such stock serves to holdactuating bar 48 in its proper place along the side of trigger guard 4.

In this modification, as previously pointed out,

actuating bar 48 is connected to the operating slide II at all times andtherefore moves with such slide. In automatic fire, lug 33 passesthrough recess I5 on the side of hammer 34 as bolt 3 recoils-to rotatehammer 34 to the cooked position. Cam 53 is disengaged from stud 44,hence the bias of spring 46 rotates hammer latch 43 in acounterclockwise direction as shown in Fig. 7. Thus lug 33 of suchhammer latch engages hammer 34 to hold it in cocked position. On thecounter-recoil stroke, slide II returns to its forward position carryingwith it actuating 55 bar 48. As slide II nears the end of its stroke,after the bolt has been locked, cam 53 strikes stud 44 thereby rotatinghammer latch 43 upwardly in a clockwise direction. Thus lug 33 isdisengaged from hammer 34', permitting such hammer 0 to go forwardly tostrike the firing pin (not shown) thereby effecting discharge of thecartridge only after bolt 3 has been fully locked. Operation of the searby manipulation of selector 23 to selectively provide semi-automatic andfull automatic fire is identical to that above described.

A third modification of a fire control mechanism embodying thisinvention is shown in assembled relation in Figs. 13 and 15. Such modi-'fication essentially comprises an alternate form of actuating bar. Thesear and trigger mechanism, including the selector, are identical tothat used in the-two aforedescribed modifications.

In this modification an actuating bar 55 (Fig.

7 14) is provided which is mounted on the right hand side of triggerguard 4. Such bar is pivotally mounted to the trigger guard at theforward end thereof by transverse pin 1. An offset, verticallyupstanding arm 56 of actuating bar 55 rests within a recess 51 providedin slide I I. The rear end 58 of bar 55 is substantially offset so thatsuch rear portion will lie adjacent the right side of hammer 34. Anarcuate cam surface 59 is provided on the bottom of the rear portion 58of bar 55. On the extreme rear end of offset portion 58 a notch 60 isprovided for a purpose to be presently described.

A headed stud GI is secured to the side of hammer 3t. Cam surface 59rides on the top side of stud El. A torsion spring 62 is provided tobias actuating bar 55 downwardly as will-be presently described. One endof such spring rests on top of bar 55 while the other end is secured tothe front end of trigger guard 4.

In the fired position as shown in Fig. 13, earn 59 overlies stud 6|.Upon rearward movement of the reciprocating bolt 3, hammer 3a is drivenrearwardly by the bolt 3 to its cocked position. 'Cam 59 is held incontact with stud Si by the bias of torsion spring 52. During automaticfire, trigger H, of course, is held rearwardly, therefore sear 22 willnot engage sear notch 38, hence hammer 34 will tend to follow bolt 3forwardly, such hammer being urged in the forward direction by thehammer spring. When hammer 34 reaches its cocked position, stud 8! movesoff cam surface 58 and into notch 6%) of bar 55. Bar 55 is held in thisposition by spring 62. Thus in effect, actuating bar 55 itself functionsas a scar relative to the hammer. On the contourreooil stroke of slideH, therefore, hammer 3 3 will be held in the cocked position by thenotch 69 provided at the rear end of bar 55. When. however, slide llcontacts the upper end of arm 56 provided on the forward end of bar 55,the rear end of bar 55 will be rotated about transverse pin 1 in aclockwise direction. This movement of bar 55 raises notch 58 out ofengagement with stud fil thereby permitting hammer 34 to be drivenforwardly, thus effecting discharge of the succeeding cartridge. As inthe other modifications, when the sear '22 is in position forsemi-automatic fire, bar 55 is inoperative except when the operatingslide fails to return to battery. When the bolt and hence the operatingslide fails to return to battery, bar 55 blocks hammer 34 therebypreventing premature discharge of the firearm.

A further modification of the fire control mechanism is shown inassembled relation in Figs. 16 and 18. Here again the identical searrelease mechanism is utilized for semi and full automatic fire,including the eccentric means for efiecting such change. This particularmodification utilizes a substantially diiferent hammer latch to restrainhammer 34 from following the bolt forwardly during automatic fire.

Such hammer latch is shown at 63 and compises a lever-like member, therear end 64 of which is oifset as shown in Fig. 17 so that such end willlie against the right face of hammer 3%. The top surface of the rear endportion 65 of latch 63 is rounded as shown at 55. Such surface isrounded to permit a transverse stud 6! on the hammer to ride along suchcurved surface. The extreme rear end of latch 63 is squared as shown at66. The forward end of latch 63 is rounded and is pivotally mounted totrigger guard d by transverse pin l. A short distance to the rear of pin1 a stud 61 is suitably and rigidly secured 8 to latch 53. Latch 63 israised upwardly'by a torsion spring 30 secured to pin '1 to engage studst to hold hammer 3a in the cooked position. A cam bar 59 comprising aforward portion 68 and a rearwardly extending spring-like arm portion itis provided to actuate latch 63. On the forward end of cam bar Gdanupstanding lug H is provided, the top of which is bent inwardly as shownat E2 ,to engage the top of operating slide H. The rear end of lug H islikewise bent inwardly to'engage the front surface of slide I therebyproviding means for attaching bar 69 to slide I i. Somewhat to the rearof lug H there is provided an inwardly projecting lug M. Such lugengages a recess iii normally provided at the rear portion of slide ii,thus securing cam bar 38 against longitudinal movement relative to slideH.

The extreme, rear end of arm 79 is sloped downwardly as shown at 73.Such sloped surface acts as a earn as will be presently described. Thesloped end it of cam bar 69 is located to the rear of stud 6"! on hammerlatch 53 so that such sloped end contacts stud 63 only when slide H ispractically at its extreme forward position.

As previously mentioned, the hammer latch is provided to restrain thehammer from following the bolt forwardly to the closed position untilthe bolt is locked, thus preventing premature discharge of the cartridgein full automatic fire. Cam bar 69 reciprocates with slide Ii. On therecoil stroke of slide i i and hence bolt 3, hammer 3 2 is of courserotated to the cooked position. While hammer Sfiiis rotated to suchposition, stud E l passes over the arcuate surface on the rear end 56 oflatch 63 and engages squared end 66 of such latch. Assuming trigger 21is held rearwardly and selector 23 is in its automatic fire position,sear :22 cannot engage sear notch 38 of hammer t l, as previouslyexplained, therefore hammer 3d starts to rotate forwardly due to thebias of hammer spring to. However, stud 6| contacts the end as of latch83 and the hammer is held in the cocked position shown in Fig. 18.

Latch 63 is restrained from rotating in a clockwise direction by theunderside of the receiver. As slide H moves forwardly, locking the bolt,the sloped canr-lilce surface E3 of arm l'il strikes stud s? and latch63 is forced downwardly. This forces the end 66 of the latch todisengage from stud SI of the hammer. When such disengagement iseffected, slide i i has reached the limit of its forward movement, hencebolt 3 is securely locked, and hammer 3 3 is then free to effectdischarge of the cartridge without danger of premature ignition.

From the foregoing description it is readily apparent to one skilled inthe art that a simple, effective fire control mechanism to permit fullautomatic fire or semi-automatic fire is hereby provided. Further, suchmechanism can be readily adapted to firearms arranged to fire onlysemi-automatically or such mechanism can be readily adapted to any newdesign of firearm requiring selective full or semi-automatic firecontrol. It is also apparent that a positive hammer latch is providedwhich insures that the hammer of the firearm is safely blocked at alltimes until the bolt of such firearm is securely locked in batteryposition. Thus premature discharge of the firearm in an unsafe positionof the bolt is eliminated.

I claim:

In an automatic firearm having a receiver, a bolt reciprocable thereinforwardly to and rear- 9 wardly from a battery position, a reciprocableoperating member for the bolt and a spring biased hammer pivoted in saidreceiver and movable by the bolt to its cocked position, the improvementcomprising, an actuating bar slidably mounted on the receiver adjacentthe operating member, a

pair of projections on said actuating bar respectively disposed in thepath of rearward and forward movement of the operating member Wherebysaid actuating bar is moved rearwardly as the operating member moves tocounter-battery position and forwardly as the operating member moves tobattery position, a hammer latch pivotally mounted on the receiveradjacent said hammer, a latching projection on said hammer latchengageable with said hammer in its cocked position, said actuating barhaving a cam slot therein adjacent said hammer latch, a projecting studon said hammer latch engageable in said cam slot, said cam slot beingconstructed and arranged to pivot said hammer latch to engage said i V wlatching projection with said hammer as the operating member moves intocounter-battery position and to release said hammer as the operatingmembermoves into battery position.

ALONZO F. GAIDOS.

" REFERENCES CITED The following references are of record in the file ofthis patent:

